Application of DRASTIC and Modified DRASTIC Models for Modeling Groundwater Vulnerability of Malda District in West Bengal

Abstract

Groundwater is one of the most important freshwater resources in our daily life. Under the background of global climate change, untreated rate of urbanization, human interferences and policy variations affect the change of global and local groundwater quality which is very common in developing countries like India. Hence, protecting groundwater from different types of contamination is the most accurate and appropriate measures of groundwater conservation. The main objectives of this work are to assess the groundwater vulnerability of Malda district using DRASTIC and modified DRASTIC methods. Seven influencing factors groundwater depth, net recharge, aquifer material, soil media, topography, the impact of vadose zone and hydraulic conductivity were used to complete DRASTIC method, agricultural DRASTIC, land use DRASTIC and AHP land use DRASTIC methods. The multi-model approach has been used to identify the best vulnerability model. For modeling Land use DRASTIC and AHP Land use DRASTIC, the land use layer was added with other layers. The groundwater vulnerability zone has been divided into three categories like high, moderate and low. High-vulnerability zones were found in the northern and southern parts, moderate zones were found in the middle part of the district, and the low-vulnerability zones in the eastern part of the district. The vulnerability model was validated using the ROC curve and Friedman test. The AHP land use DRASTIC shows better performance compared to other vulnerability models.